This invention relates to the field of arc welding, and in particular to welding cast iron with one inch welding rods thereby simplifying the repair of large cracks or the rebuilding of sections of a cast iron workpiece that has been chipped or worndown.
Prior art cast iron welding apparatus designs have been aimed at using smaller welding rods and using welding machines capable of providing the required amperage. No welding apparatus designs have provided for utilizing one inch welding rods and the welding machines to supply the required current in the range of 3000 amperes.
The problem with prior art cast iron welding apparatus is that they cannot from a practical standpoint repair large cracks in cast iron or rebuild large sections of a cast iron workpiece that have been worndown or broken off. It is common to replace rather than repair cast iron assemblies once they have been damaged beyond the repair capabilities of prior art welding apparatus.
Examples of prior art devices include those disclosed in the following United States Patents:
U.S. Pat. No. 4,590,357 discloses a welding apparatus that combines an alternator of a vehicle with a battery pack. A jack plus on one end of an electric holder is connectable to one of a choice of twelve inductor jacks thereby varying the current supplied to a one-quarter inch welding rod from 300 to 40 amps. One problem with this design is that it is limited to supplying a maximum current of 300 amps. The 300 amp maximum current rating cannot supply a one inch cast iron welding rod which requires approximately 3000 amps to operate. The welding apparatus described in the patent can provide enough current to a one quarter inch diameter welding rod, but a welding rod of this size is not capable of repairing large cracks or rebuilding sections of a cast iron workpiece that have been worndown or broken off.
U.S. Pat. No. 4,388,512 discloses a welding method and apparatus for use in the electronics field to weld a small diameter aluminum wire to an IC chip for example. It uses two separate power supplies, one to supply a low voltage below the threshold needed to ignite an arc between the electrode and end of an aluminum wire on which a spherical ball is to be formed, and a second power supply that provides a short impulse voltage sufficient to ignite the arc after which it cuts out letting the initial low voltage power supply maintain the arc until the spherical ball is formed at the end of the aluminum wire.
U.S. Pat. No. 3,792,225 discloses a welding system for "dip transfer" or "short circuit" welding in which two separate power supplies are used, one to provide the initial arc and the second to take over and supply increased current to the short circuit "bridge" formed by each molten drop between the electrode and work piece for a short period of time until a sensing unit senses increased resistance when the "bridge" piece begins to reduce in cross-section or "neck", at which time the second power supply cuts out.
U.S. Pat. No. 3,278,721 discloses a multi-station type of welding system power by one A.C. generator which in turn feeds three rectifier power supply units to provide three different sources of D.C. output which are connected to a common bus bar to which a distribution cable is connected to carry power to several outlet units, each of which in turn have six separate control stations for selecting different current levels to apply to a welding electrode connected thereto, such amps ranging from 50 amps output down to 10 amps output.
U.S. Pat. No. 3,059,164 discloses a A.C. supplied welding system with a D.C. converter to change the A.C. input to D.C. output for direct current welding. The patent further discloses a cooling system within the converter that varies cooling capability directly with current demand.
U.S. Pat. No. 1,684,317 discloses an early type of welding system for use with an alternating power supply in which two transformers are connected to the three phase supply line, both transformers being connected to the middle supply line conductor but one having the opposite terminal of its primary winding connected to one of the outer supply line conductors and the other transformer having its opposite primary winding terminal connected to the other one of the outer supply line conductors.